Publication date: Aug 2006
Abstract:
We determine the influence of a nonzero cosmological constant on dynamical stability of spherically symmetric perfect fluid configurations. The equations governing small radial oscillations and the related Sturm-Liouville eigenvalue equation for eigenmodes of the oscillations are generalised for the case of nonzero cosmological constant. The Sturm-Liouville equation is then applied in the case of polytropic equation of state. Based on this approach, the dependence of the critical value of adiabatic index on relativistic parameter (defined as ratio of central pressure to central energy density) is established for values of polytropic index 3/2 and 3 and for both repulsive and attractive cosmological constant using numerical computations. It is shown that a repulsive cosmological constant rises the critical adiabatic index and decreases the critical radius under which the dynamical instability occurs.
Authors:
Hledík, S.; Stuchlík, Z.;